/**
 * @file
 * SLIP Interface
 *
 */

/*
 * Copyright (c) 2001-2004 Swedish Institute of Computer Science.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the Institute nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * This file is built upon the file: src/arch/rtxc/netif/sioslip.c
 *
 * Author: Magnus Ivarsson <magnus.ivarsson(at)volvo.com>
 */

/*
 * This is an arch independent SLIP netif. The specific serial hooks must be
 * provided by another file. They are sio_open, sio_read/sio_tryread and sio_send
 */

#include "netif/slipif.h"
#include "lwip/opt.h"

#if LWIP_HAVE_SLIPIF

#include "lwip/def.h"
#include "lwip/pbuf.h"
#include "lwip/sys.h"
#include "lwip/stats.h"
#include "lwip/snmp.h"
#include "lwip/sio.h"

#define SLIP_BLOCK     1
#define SLIP_DONTBLOCK 0

#define SLIP_END     0300 /* 0xC0 */
#define SLIP_ESC     0333 /* 0xDB */
#define SLIP_ESC_END 0334 /* 0xDC */
#define SLIP_ESC_ESC 0335 /* 0xDD */

#define SLIP_MAX_SIZE 1500

enum slipif_recv_state
{
    SLIP_RECV_NORMAL,
    SLIP_RECV_ESCAPE,
};

struct slipif_priv
{
    sio_fd_t sd;
    /* q is the whole pbuf chain for a packet, p is the current pbuf in the chain */
    struct pbuf *p, *q;
    enum slipif_recv_state state;
    u16_t i, recved;
};

/**
 * Send a pbuf doing the necessary SLIP encapsulation
 *
 * Uses the serial layer's sio_send()
 *
 * @param netif the lwip network interface structure for this slipif
 * @param p the pbuf chaing packet to send
 * @param ipaddr the ip address to send the packet to (not used for slipif)
 * @return always returns ERR_OK since the serial layer does not provide return values
 */
err_t
slipif_output(struct netif *netif, struct pbuf *p, struct ip_addr *ipaddr)
{
    struct slipif_priv *priv;
    struct pbuf *q;
    u16_t i;
    u8_t c;

    LWIP_ASSERT("netif != NULL", (netif != NULL));
    LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));
    LWIP_ASSERT("p != NULL", (p != NULL));

    LWIP_UNUSED_ARG(ipaddr);

    priv = netif->state;

    /* Send pbuf out on the serial I/O device. */
    sio_send(SLIP_END, priv->sd);

    for (q = p; q != NULL; q = q->next)
    {
        for (i = 0; i < q->len; i++)
        {
            c = ((u8_t*)q->payload)[i];
            switch (c)
            {
            case SLIP_END:
                sio_send(SLIP_ESC, priv->sd);
                sio_send(SLIP_ESC_END, priv->sd);
                break;
            case SLIP_ESC:
                sio_send(SLIP_ESC, priv->sd);
                sio_send(SLIP_ESC_ESC, priv->sd);
                break;
            default:
                sio_send(c, priv->sd);
                break;
            }
        }
    }
    sio_send(SLIP_END, priv->sd);
    return ERR_OK;
}

/**
 * Static function for easy use of blockig or non-blocking
 * sio_read
 *
 * @param fd serial device handle
 * @param data pointer to data buffer for receiving
 * @param len maximum length (in bytes) of data to receive
 * @param block if 1, call sio_read; if 0, call sio_tryread
 * @return return value of sio_read of sio_tryread
 */
static u32_t
slip_sio_read(sio_fd_t fd, u8_t* data, u32_t len, u8_t block)
{
    if (block)
    {
        return sio_read(fd, data, len);
    }
    else
    {
        return sio_tryread(fd, data, len);
    }
}

/**
 * Handle the incoming SLIP stream character by character
 *
 * Poll the serial layer by calling sio_read() or sio_tryread().
 *
 * @param netif the lwip network interface structure for this slipif
 * @param block if 1, block until data is received; if 0, return when all data
 *        from the buffer is received (multiple calls to this function will
 *        return a complete packet, NULL is returned before - used for polling)
 * @return The IP packet when SLIP_END is received
 */
static struct pbuf *
slipif_input(struct netif *netif, u8_t block)
{
    struct slipif_priv *priv;
    u8_t c;
    struct pbuf *t;

    LWIP_ASSERT("netif != NULL", (netif != NULL));
    LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));

    priv = netif->state;

    while (slip_sio_read(priv->sd, &c, 1, block) > 0)
    {
        switch (priv->state)
        {
        case SLIP_RECV_NORMAL:
            switch (c)
            {
            case SLIP_END:
                if (priv->recved > 0)
                {
                    /* Received whole packet. */
                    /* Trim the pbuf to the size of the received packet. */
                    pbuf_realloc(priv->q, priv->recved);

                    LINK_STATS_INC(link.recv);

                    LWIP_DEBUGF(SLIP_DEBUG, ("slipif: Got packet\n"));
                    t = priv->q;
                    priv->p = priv->q = NULL;
                    priv->i = priv->recved = 0;
                    return t;
                }
                continue;
            case SLIP_ESC:
                priv->state = SLIP_RECV_ESCAPE;
                continue;
            }
            break;
        case SLIP_RECV_ESCAPE:
            switch (c)
            {
            case SLIP_ESC_END:
                c = SLIP_END;
                break;
            case SLIP_ESC_ESC:
                c = SLIP_ESC;
                break;
            }
            priv->state = SLIP_RECV_NORMAL;
            /* FALLTHROUGH */
        }

        /* byte received, packet not yet completely received */
        if (priv->p == NULL)
        {
            /* allocate a new pbuf */
            LWIP_DEBUGF(SLIP_DEBUG, ("slipif_input: alloc\n"));
            priv->p = pbuf_alloc(PBUF_LINK, (PBUF_POOL_BUFSIZE - PBUF_LINK_HLEN), PBUF_POOL);

            if (priv->p == NULL)
            {
                LINK_STATS_INC(link.drop);
                LWIP_DEBUGF(SLIP_DEBUG, ("slipif_input: no new pbuf! (DROP)\n"));
                /* don't process any further since we got no pbuf to receive to */
                break;
            }

            if (priv->q != NULL)
            {
                /* 'chain' the pbuf to the existing chain */
                pbuf_cat(priv->q, priv->p);
            }
            else
            {
                /* p is the first pbuf in the chain */
                priv->q = priv->p;
            }
        }

        /* this automatically drops bytes if > SLIP_MAX_SIZE */
        if ((priv->p != NULL) && (priv->recved <= SLIP_MAX_SIZE))
        {
            ((u8_t*)priv->p->payload)[priv->i] = c;
            priv->recved++;
            priv->i++;
            if (priv->i >= priv->p->len)
            {
                /* on to the next pbuf */
                priv->i = 0;
                if (priv->p->next != NULL && priv->p->next->len > 0)
                {
                    /* p is a chain, on to the next in the chain */
                    priv->p = priv->p->next;
                }
                else
                {
                    /* p is a single pbuf, set it to NULL so next time a new
                     * pbuf is allocated */
                    priv->p = NULL;
                }
            }
        }
    }

    return NULL;
}

#if !NO_SYS
/**
 * The SLIP input thread.
 *
 * Feed the IP layer with incoming packets
 *
 * @param nf the lwip network interface structure for this slipif
 */
static void
slipif_loop_thread(void *nf)
{
    struct pbuf *p;
    struct netif *netif = (struct netif*)nf;

    while (1)
    {
        p = slipif_input(netif, SLIP_BLOCK);
        if (p != NULL)
        {
            if (netif->input(p, netif) != ERR_OK)
            {
                pbuf_free(p);
                p = NULL;
            }
        }
    }
}
#endif /* !NO_SYS */

/**
 * SLIP netif initialization
 *
 * Call the arch specific sio_open and remember
 * the opened device in the state field of the netif.
 *
 * @param netif the lwip network interface structure for this slipif
 * @return ERR_OK if serial line could be opened,
 *         ERR_MEM if no memory could be allocated,
 *         ERR_IF is serial line couldn't be opened
 *
 * @note netif->num must contain the number of the serial port to open
 *       (0 by default)
 */
err_t
slipif_init(struct netif *netif)
{
    struct slipif_priv *priv;

    LWIP_DEBUGF(SLIP_DEBUG, ("slipif_init: netif->num=%"U 16_F "\n", (u16_t)netif->num));

    /* Allocate private data */
    priv = mem_malloc(sizeof(struct slipif_priv));
    if (!priv)
    {
        return ERR_MEM;
    }

    netif->name[0] = 's';
    netif->name[1] = 'l';
    netif->output = slipif_output;
    netif->mtu = SLIP_MAX_SIZE;
    netif->flags |= NETIF_FLAG_POINTTOPOINT;

    /* Try to open the serial port (netif->num contains the port number). */
    priv->sd = sio_open(netif->num);
    if (!priv->sd)
    {
        /* Opening the serial port failed. */
        mem_free(priv);
        return ERR_IF;
    }

    /* Initialize private data */
    priv->p = NULL;
    priv->q = NULL;
    priv->state = SLIP_RECV_NORMAL;
    priv->i = 0;
    priv->recved = 0;

    netif->state = priv;

    /* initialize the snmp variables and counters inside the struct netif
     * ifSpeed: no assumption can be made without knowing more about the
     * serial line!
     */
    NETIF_INIT_SNMP(netif, snmp_ifType_slip, 0);

    /* Create a thread to poll the serial line. */
    sys_thread_new(SLIPIF_THREAD_NAME, slipif_loop_thread, netif,
                   SLIPIF_THREAD_STACKSIZE, SLIPIF_THREAD_PRIO);
    return ERR_OK;
}

/**
 * Polls the serial device and feeds the IP layer with incoming packets.
 *
 * @param netif The lwip network interface structure for this slipif
 */
void
slipif_poll(struct netif *netif)
{
    struct pbuf *p;
    struct slipif_priv *priv;

    LWIP_ASSERT("netif != NULL", (netif != NULL));
    LWIP_ASSERT("netif->state != NULL", (netif->state != NULL));

    priv = netif->state;

    while ((p = slipif_input(netif, SLIP_DONTBLOCK)) != NULL)
    {
        if (netif->input(p, netif) != ERR_OK)
        {
            pbuf_free(p);
        }
    }
}

#endif /* LWIP_HAVE_SLIPIF */
